1. Field of the Invention
The present invention relates to a magnetic head using a magnetic tape as a recording medium, a method for producing the magnetic head, and a magnetic tape device.
2. Description of the Related Art
As shown in FIG. 15, in performing a recording operation on a magnetic tape 101, a helical scanning method is widely used. In the helical scanning method, a rotating drum 103 including magnetic heads 102 is rotated at a high speed, and a magnetic tape 101 is placed obliquely along a peripheral surface 103a of the rotating drum 103 in order to record information onto the magnetic tape 101. As shown in FIG. 16, according to this recording method, recording tracks 105 are defined by being inclined by a predetermined angle with respect to a transport direction L (longitudinal direction) of the magnetic tape 101.
In magnetic recording by the helical scanning method, in order to record magnetic information onto the magnetic tape 101 with a density that is as high as possible, what is called a guard bandless recording method in which gaps are not formed between adjacent recording tracks 105 is generally used. In the guard bandless recording method, in order to prevent what is called crosstalk caused by entrance of a signal from a recording track 105 that is adjacent to a recording track 105 whose magnetic information is being read, first recording tracks and second tracks are alternately formed. Information is recorded along the first recording tracks 106 and the second recording tracks 107 at different azimuth angles with respect to a longitudinal direction M of the recording tracks 106 and 107.
In order to carry out such a recording method, a magnetic head 102a and a magnetic head 102b are mounted to the rotating drum 103 at different angles (see FIG. 17). The magnetic head 102a is used to record information along the first recording tracks 106, and the magnetic head 102b is used to record information along the second recording tracks 107. When magnetic information is recorded along the first recording tracks 106 and the respective second adjacent recording tracks 107 at different azimuth angles, even if guard bands are not formed between the first recording tracks 106 and the second recording tracks 107, it is possible to reduce the effects of signals from adjacent tracks due to azimuth loss.
An inductive head using a thin-film process for increasing recording density is known (refer to, for example, Japanese Unexamined Patent Application Publication No. 2001-52304 (Patent Document 1)). In addition, an inductive head comprising a lower core layer having a protruding portion for preventing magnetic spreading in the inductive head is known to be designed for a hard disc (refer to, for example, Japanese Unexamined Patent Application Publication No. 11-328616 (Patent Document 2)).
As shown in FIG. 17, in order to record information along the first recording tracks 106 and the second recording tracks 107 of the magnetic tape 101 at different azimuth angles, the magnetic heads 102a and 102b, each comprising a rectangular upper core layer 111 and a rectangular lower core layer 112, are disposed at a rotating cylinder so that the magnetic heads 102a and 102b can magnetically record information while being tilted at two respective azimuth angles with respect to the longitudinal direction M of the recording tracks 106 and 107. Multiple recording areas 110 are formed at adjoining portions of the first recording tracks 106 and the respective second adjacent recording tracks 107 taking into consideration, for example, errors in the recording positions of the magnetic heads 102a and 102b. At the multiple recording areas 110, portions of pieces of magnetic information are written upon each other by the magnetic heads 102a and 102b. 
However, since end surfaces of the related magnetic heads 102a and 102b that oppose the magnetic tape 101 are formed with rectangular shapes, when the magnetic heads 102a and 102b are tilted by predetermined azimuth angles with respect to the recording tracks, magnetic fields that are generated at both sides of each of the magnetic heads 102a and 102b in a core width direction between the upper core layer 111 and the lower core layer 112 are tilted from the longitudinal direction of the recording tracks 106 and 107. Therefore, when magnetic information is being recorded along a second recording track 107 by the magnetic head 102b subsequent to recording magnetic information along a first recording track 106 by the magnetic head 102a, the effect of leakage magnetic fields F1 extending in the core width direction is increased, resulting in the possibility of the leakage magnetic field F1 extending considerably beyond the multiple recording area. As a result, the magnetic information recorded along the first recording track 106 may become magnetically erased, thereby producing an erased area 121 with a relatively wide width by the leakage magnetic field F1 extending beyond the multiple recording area 110. The erased area 121 essentially reduces track width, resulting in the possibility of an S/N ratio of a reproduction signal being reduced when recorded information is read out from the magnetic tape 101.